Alternating-current motor.



PATENTED MAY 26, 1903.

C. P. STEINMETZ.

ALTERNATING CURRENT MOTOR.

APPLIOATI ON FILED T12R12 1903.

2SHEETS-SHEET 1.

N0 MODEL.

' lnverfitor. Charles 'P. Steinmetz Witnesses n4: nonms runs 00..Pfimourka, WASHINGTON u. n.

PATENTED MAY 26, 1903 C. P. STEINMETZ. ALTERNATING CURRENT MOTOR.

AIfPLIOATION FILED FEB. 12. 1903.

2 SHEETS-SHEET 2.

H0 MODEL.

Fig. 4.

Fig.5.

Inventor. Charles P. Steinmetz.

Witnesses UNITED STATES Patented May 26, 1903.

PATENT OFFICE.

CHARLES P. STEINMETZ, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ALTERNATlNG-CURRENT MOTOR.

SPECIFICATION forming part of Letters Patent N 0. 729,441, dated May 26,1903.

Application filed February 12, 1903. Serial No. 143,001- (No modelJ I Toall whom it may concern:

Be it known that I, CHARLES P.7STEINMETZ, a citizen of the UnitedStates, residing at Schenectady, in the county of Schenectady, State ofNew York, have invented certain new and usefulImprovements inAlternating-Current Motors, of which the following is a specification.

My present invention relates to self-starting single-phasealternating-current motors, and has for its object to so organize analternating-current motor system that the motor may be convenientlystarted from a singlephase source of supply and may be operated with ahigh power factor.

The invention relates to that class of motors in which for purposes ofregulation the secondary member is provided with a directcurrentwindingthat is, with a winding suitably connected to the segments of acommutator such as is used in direct-current ma chines-and comprises asystem of control for a motor of the class above referred to, the systembeing so organized that the motor may be started from a single-phasesource of supply and may be efficiently operated from such a sourceafter it has been brought up to speed.

In carrying out my invention I utilize the direct-current winding forstarting, placing it in such relation to the primary winding and thesource of supply that a starting torque will be produced, and after themotor is running I connect the windings to the source of supply and toeach other in such a manner that the most efficient operating conditionsare obtained.

My invention will be better understood by reference to the followingdescription, taken in connection with the accompanying drawings, whileits scope will be pointed out in the appended claims.

In the drawings, Figure l is a diagram illustrating a motor of the typeto which my invention relates, together with a suitable controller forconnecting the motor-windings in accordance with the principles of myinvention. Fig. 2 is a simplified diagram showing the connections of themotor in Fig. 1 when the controller is in its first operative position.Fig. 3 is a simplified diagram showing the connections of the motor inFig. 1 when the controller is in the final running position. Fig. 4 is adiagram illustrating another embodiment of my invention, in which thestarting connections are difierent from those shown in Fig. 1; and Fig.5 is a simplified diagram showing the starting connections for thesystem illustrated in Fig. 4.

Referring first to Figs. 1, 2, and 3, M indicates an alternating-currentmotor, the primary member of which is provided with a winding P, shownas a three -phase star-com nected winding comprising the sections a, b,and c. The secondary member S is provided with the usual squirrel-cageor other short-circuited winding W, and also with a winding D of thedirect-current type connected to the segments of a commutator it, uponwhich bear three brushes d, e, and f, displaced by one hundred andtwenty degrees from each other and arranged with relation to the polesof the primary member in a manner which will be explained later. Forconvenience in illustration the winding D is indicated as aring-winding. In practice a drum-winding is preferably employed, andthis winding should be placed beneath the conductors of thesquirrel-cage Winding. In order to control the flow of current at themoment of starting,a resistance R is provided.

For controlling the connections of the motor-windings a switch C isprovided, which may be of any desired type. The particularcontrolling-switch illustrated in the drawings is of the controllertype, having a cylinder carrying movable contacts arranged to engagewith a series of fixed contacts or brushes as the cylinder is rotated.The drawings show a development of the fixed and movable contacts of thecontrolling-switch, the fixed contacts being represented by the smallcircles 6 to 18, and the movable con tacts by rectangles, which areelectrically interconnected, as indicated by thelin'e's joining thecontacts on the drawings. The operative positions of the fixed contactson the rectangular movable contacts are indicated by the lines 11 to5 5.A B represent the mains of a single-phase source of supply.

As shown, the controller C is in its off position and the circuitthrough the motorwindings is broken at the controller-contacts.

If now the controller be moved into its first operative position, wherethe fixed contacts 6 to 18 lie along line 11, acircuit may be tracedasfollows: Starting from the supply-main B the circuit leads through fixedcontacts 6 and 7 and the corresponding movable contacts to conductor 7,thence through resistance R to conductor 11, through fixed contacts 11and 12 and the cooperating movable contacts to conductor 12, thence byway of brushes d and 6 through the direct-current winding on thesecondary member of the motor M to conductor 14, through fixed contacts14 and 16 and the corresponding movable contacts to conductor 16, andthence through sections a and c of the primary winding P and conductor19 to the othersupply-main A. The connections for this position of thecontroller are illustrated by a simple diagram in Fig. 2. This is thefirst or starting position of the motor-controller and, as will be seenfrom an inspection of the diagram of Fig. 2, the connections are suchthat the motor will start as an alternating-current motor of thedirect-current type, the flow of current through the motor-windingsbeing controlled by means of the resistance R. The successive positionsof the controller (indicated by the vertical lines 2 2 to 4 4,inclusive) operate merely to cut out sections of the resistance R, sothat in the position or" the controller-contacts (indicated by thevertical line 4 4) this resistance is cut out of circuit.

Now if the controller is moved into the final running position,where thefixed contacts lie along the line 5 5, circuits may be traced asfollows: Starting from the supply-main B, a circuit leads through fixedcontacts 6, 10, 11, and 16 and through the corresponding movablecontacts to conductor 16, and thence through the sections a and c of theprimary winding P to the conductor 19, which is directly connected tothe supply-main A. Also in this position of the controller the points 1,1", and 1 in the primary winding are connected directly to thecommutator-brushes d, e, and fon the secondary member, these connectionsbeing completed through fixed contacts 12 to 15 and 17 and 18 and thecorresponding movable contacts in a manner which will be evident from aninspection of the circuit connections in Fig. 1. The circuit connectionsestablished in this the final running position of the controllerO areindicated by a simple diagram in Fig. 3 of the draw- 'ings,from which itwill be seen that two of the terminals of the three-phase primarywinding are connected directlyto the single-phase supplymains and thatthe commutatorbrushes are each connected to an intermediate point in oneof the three-phase windings on the primary member.

With the connection shown in Fig. 3 of the drawings if thecommutator-brushes d, e,a'nd

f are properly positioned with reference to the poles of the primarymember the motor may be operated at a veryhigh power factor,

the magnetizing-current for the motor being supplied through thedirect-current winding on the secondary member in a manner now wellunderstood. The voltage necessary to be impressed upon thedirect-current winding in order to produce the desiredmagnetizing-current is in general less than the voltage of the source ofsupply and may evidently be adjusted to any desired value by properlypositioning the points of connection 1 1", and 1 in the primary winding.

In Fig. 4 I have illustrated anotherembodiment of my invention, in whichthe connections for starting are so arranged that the motor will bestarted as a repulsion-motor instead of as a motor of the direct-currenttype, as indicated in Figs. 1 and 2. In this figure also I have shown inplace of the controller 0 of Fig. 1 a simple double-throw switch, whichin one of its positions completes the necessary circuit connections forstarting the motor and in its other position completes the connectionsfor running. The resistance R is in this figure controlled by means of aseparate switch F.

With the switch in the position shown in the drawings circuits may betraced as follows: Starting from the supply-conductor B a circuit leadsthrough the conductor 1 and through the sections at and c of the primarywinding P to the other supply-main A. Also starting from the brush f acircuit may be traced through the switch Fand the resistance R to one ofthe members of the switch E, and thence through conductors 4 and '3 tothe brush (Z. With the switch E in the position shown, therefore, two ofthe terminals of the primary winding are connected to the singlephasesource of supply and the direct-current winding on the secondary memberis short-circuited through two of the commutator-brushes and all or aportion of the resistance R in such a manner that the motor will startas a repulsion-motor. If after the motor has been started the switch Eis moved into its other operative position, the resistance R will be cutout of circuit and each of the three commutator-brushes will beconnected to one of the intermediate points 1, 1 and 1 in the primarywinding of the motor, the connections for the primary winding remainingas before.

In lieu of connecting the commutatorbrushes to intermediate points in asingle primary winding I may of course wind the portion to which thebrushes are connected as a separate winding in inductive relation to themain winding P. Other changes in the connectionsmay evidently be madewithout affecting the operation of the system, and I aim in the claimshereto appended to cover all modifications which do not involve adeparture from the spirit and scopev of my invention.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is-

1. The combination with an induction-motor having its primary memberprovided with a multiphase winding and its secondary mem-.

ber with a short-circuited winding and with a winding of thedirect-current type, of means for connecting the motor-windings to asinglephase source of supply in such a manner that a starting torquewill be produced.

2. The combination with an induction-motor having its primary memberprovided with a multiphase winding and its secondary mem ber with ashort-circuited winding and with awinding of the direct-currenttype, ofmeans for connecting the multiphase winding to a single-phase source ofsupply and forconnecting the direct-current winding in such relationwith respect thereto that astarting torque will be produced.

3. The combination with an induction-motor having its primary memberprovided with a multiphase winding and its secondary member with ashort-circuited winding and with a winding of the direct-current type,of a controlling-switch having its contacts constructed and arranged tofirst connect the multiphase winding to a single-phase source of supplyand the direct-current windingin such relation with respect thereto thata starting torque will be produced and thereafter to connect themultiphase winding to the singlephase source and the direct-currentwinding to suitable points in the said multiphase winding.

4. The combination with an induction-motor having its primary memberprovided with a multiphase winding and its secondary member with ashort-circuited winding and with a winding of the direct-current typeconnected through its commutator to brushes so positioned that themagnetizing-current for the motor may be supplied through the lastwinding in such a manner as to increase the power factor of the motor,of a controllingswitch having its contacts constructed and arranged tofirst connect the multiphase winding to a single-phase source of supplyand to connect the direct-current winding in such relation withrespectthereto that a starting torque will be produced and thereafter toconnect the multiphase winding to the single-phase source and thecommutator-brushes to suitable points in the multiphase winding on theprimary member.

5. The combination with an induction-motor having its primary memberprovided with a three-phase winding and its secondary member with ashort-circuited winding and with a winding of the direct-current typeconnected through its commutator to brushes so positioned that themagnetizing-current for the motor may be supplied through the lastwinding in such manner as to increase the power factor of the motor, ofa controlling-switch having its contacts so constructed and arrangedthat in one position two of the terminals of the three-phase primarywinding will be connected to the single-phase source of supply and thedirect-current winding will be connected in such relation with respectto the three-phase primary winding that a starting torque will beproduced and in another position so that two of the terminals of thethree-phase winding will be connected to the single-phase source ofsupply and the commutator-brushes to suitable points in the winding onthe primary member.

In witness whereof I have hereunto set my hand this 11th day ofFebruary, 1903.

CHARLES P. STEINMETZ- Witnesses:

BENJAMIN B. HULL, HELEN ORFORD.

